With the continuous development of oil fields, most of domestic oil fields have entered an intermediate or high water-cut development stage, and the liquid extracted from oil fields generally contains more than 90% of water. The continuous increase in water content leads to a rise in the expense of lifting the liquid extracted, making production cost get higher and higher; when the extraction of the mixture liquid costs more than the profits brought by the oil separated from the mixture liquid, oil wells will be on the verge of their economic exploitation limits and therefore forced to shut down. Thus, the use of an oil-water pre-separation device in oil wells is of great significance to the improvement of the recovery rate of oil wells.
In order to meet the demand for oil, domestic oil exploration will mainly rely on the development of offshore oil, inevitably extending to deep water, extremely deep water; the major technical bottleneck which restricts the oil exploration in a deep water region lies in an efficient oil-water separation technology for the use in a deep water environment. The high-pressure environment of deep-water disables a bulky tank separator and requires the use of a compact tubular separator.
The separation principle of existing oil-water pre-separation equipment mainly lies in gravity and centrifugation, for example, an oil-water separator based on the principle of gravity is disclosed in the prior Patent Application No. CN1078291A, however, in practical production, it is usually needed to separate a great amount of oil-water mixture quickly, while the principle of gravity, although being an effective separation means, is relatively slow in processing speed. In the prior Patent Application No. CN1078292A, there is disclosed a downhole oil-water separator which accelerates the separation of oil from water by generating a cyclone field with dynamic blades, and in the authenticated Utility Model No. CN2601121Y, there is disclosed an oil-water pre-separation device for extracted liquid which separates oil from water with the cyclone generated through the corotation of a separating impeller and a working barrel. The aforementioned separation devices, both of which realize oil-water separation based on the principle of centrifugation, are commonly equipped with a moving component and are therefore difficult to be maintained.